In-situ synthesis of biochar-based transition metal oxide composite catalysts for highly photothermal oxidation single- and multi-component indoor VOCs

Although the photothermal synergistic catalysis technology shows great potential for eliminating indoor volatile organic compounds (VOCs), its catalytic degradation of multi-component VOCs with different polarities still faces challenges such as insufficient catalytic oxidation performance and weak selective adsorption. This study innovatively utilized waste silk textiles as the sustainable carbon source to successfully synthesize a biochar-based transition metal oxide composite catalyst via an in-situ growth method, constructing the MnO x /C/TiO 2 ternary composite catalyst. The experimental result demonstrated that the optimal catalyst (TSTMn-0.05) had remarkable synergistic removal efficiency for the mixed pollutant of CH 2 O and C 7 H 8 under photothermal synergistic catalysis, and featured the degradation rates of 98.9 % and 85.2 % respectively within 90 min for CH 2 O and C 7 H 8 Its excellent performance stems from the broad-spectrum adsorption and enrichment of various polar VOCs by the biochar matrix, the unique heterojunction structure of the catalyst, and the synergistic effect of the multivalent redox cycling of Mn ions and the photothermal effect. During the photothermal synergy process, multiple effects jointly promote the efficient separation of photogenerated carriers and the generation of a large number of reactive oxygen species (ROS), thereby driving the deep mineralization of VOCs. This study not only achieves the high-value resource utilization of waste textiles but also provides a new strategy for developing advanced photothermal catalysts capable of efficiently purifying complex and multi-component VOCs. • MnO x /C/TiO 2 (TSTMn) catalysts were synthesized via in-situ growth of transition metal oxides on biochar substrate. • Biochar-based (multi-) transition metal oxide composite structure effectively promoted catalyst’ photothermal synergistic effects. • TSTMn exhibited desirable removal efficiencies for both single- and multi-component indoor VOCs. • The degradation pathways of CH 2 O and C 7 H 8 mixture under TSTMn-0.05 were consistent with those observed for their single-component counterparts.